This one is for the music geeks out there. I just stumbled across this article in Wired magazine from October of 2008, detailing how a university professor used mathematics to figure out the notes being played in that famous opening chord from "A Hard Day's Night".
(Spoiler alert: the chord turns out to be an A-flat-major-diminished-9th-add-2-suspended-4th-circular-sharp-tritone-really-bloody-difficult-7th)
